Principles of Biology Lab
Principles of Biology Lab BIO 121
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This 9 page Class Notes was uploaded by Reta Nicolas on Sunday October 11, 2015. The Class Notes belongs to BIO 121 at Eastern Kentucky University taught by Amy Braccia in Fall. Since its upload, it has received 19 views. For similar materials see /class/221461/bio-121-eastern-kentucky-university in Biology at Eastern Kentucky University.
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Date Created: 10/11/15
After studying this lecture and text chapter 15 students should be able to Brie y explain how information flows from gene to protein and relate this to the Central Dogma of Molecular Biology Explain how RNAdiffers from DNA Distinguish between transcription and translation and compare where transcription and translation occur in bacteria and in eukaryotes Explain how MA 39 39 39 39 role ofthe promoter the terminator and the transcription unit begin Describe the Explain the general process of transcription includingthe three major steps ofinitiation elongation and termination Explain how RNA is modified after transcription in eukaryotic cells De ne quotcodonquot and explain the relationship between the linear sequence of codons on mRNA and the linear sequence of amino acids in a polypeptide Explain why polypeptides begin with methionine when they are synthesized Explain the significance of the reading frame duringtranslation Describe the structure and function oftRNA Explain how tRNA is joined to the appropriate amino acid Describe the structure and functions of ribosomes Describe the process oftranslation including initiation elongation and termination and explain what is nee ed Explain what determines the primary structure ofa protein and describe how a polypeptide must be modi ed before it becomes fully functional Describe what determines whether a ribosomewill be free in the cytosol or attached to the rough endoplasmic reticulum Define the term 39mutation39 Give an example ofa physical and a chemical agent of mutation quot C 39 and rli tinoni h 39 39 nrl quot List and de ne the types ofsubstitutions give an example of each and note the signi cance of such changes Distinguish between a missense and a nonsense mutation 4122011 4122011 The Flow of Genetic Information from genes to proteins Key Questions 1 How do genes determine an organism s traits or what does a gene actually say 2 How is the message in DNA translated into a specific trait Nucleic Acids and Proteins Contain Information Written in Two Different Languages Nucleic acids are polymers are nucleotides 4 possible nucleotide bases each gene has a specific nucleotide sequence genes are 1001000 s of nucleotides long Proteins polypeptides are polymers of amino acids 20 pOSSIble ammo aCIds 7 7 each protein has a specific amino acid sequence arrangement and order of amino acids determines the primary structure of a protein How do cells convert genes to proteins RECALL The Central Dogma of Molecular Biology DNA codes for the production of RNA RNA codes for polypeptides and protein does not code for the production of protein Genes do not build proteins directly The Structure of RNA singlestranded nucleic acid ribosephosphate backbone Remember RNA contains gracil instead of Ihymine RNA The Bridge Between DNA and Protein Synthesis Ay wnm l l 0 Synthesis of mRNA in the w nucleus mRNA Mfgi NUCLEUS i iquoti 7 CYTOPLASM i mRNA 9 Movement of Ribosome mRNA into cytoplasm via nuclear pore 9 Synthesis of protein RNA transcribes and translates the genetic code in DNA Nuclear Nenvelope DNA v M K PremRNA RNA PROCESSING i mRNA x gPolypeptide y b Eukaryotic cell OVERVEIW The Roles of Transcription and Translation in the Flow of Genetic Information Gene 2 DNA rm molecule quot a r Gene 1 3 JJ 1 l I H kw Lb bGenera wa DNA template 3 strand Codon TRANSLATION l Protein Amino acid Transcription the synthesis of RNA under the direction of DNA RNA Processing prepping the mRNA for translation in eukaryotes Translation the synthesis of a protein under the direction of mRNA 4122011 An Overview of Transcription The process of transcription results in an RNA mRNA copy of the DNA DNA molec AL Gene 2 ule m C a r Gene 1 l j Ct l l by Gene 3 I 39 390 39 12 DNA One strand of the strand parent DNA molecule serves as the template Basepairing rules are slightly different for RNA 3 template A T ICICIAIAIAICICIGIAIGIT G G T T T G G C T C A ll imam A Roadmap to DNA and Important Terminology Important sites nucleotide sequences on D transcription Promoter region example of a common promoter in eukarotes TATAAA ta ta box Terminator region Template strand Transcription unit NA that are necessary for correct W Promoter 710 sequence Downstream Coding strand Sites on DNA are either upstream or downstream of the transcription unit The first base transcribed 1 The first base upstream of the start site 1 4122011 4122011 Initiation beginnin g Promoter Transcription unit transcription 3 g 1 e g Start point DNA RNA polymerase 0 Initiation RNA polymerase the enzyme that reads genes and copies the information 5 I 3 i aquot 5 Into mRNA RNA Template strand 3320quot transcript 01 DNA binds to DNA at promoter region does NOT require a primer 01 H l 0 ooenzyme pries the strands of DNA apart g gjme 6 Prokaryotic RNA polymerase I Pr m ter Transcription unit lengthening mRNA 3 2 3 Start point DNA RNA pol joins nucleotides as RNA polymerase they base pair along the DNA 0 39quot39t39at39 quot template strand 5 3 assembles mRNA in the 5 to 3 3 39 39 5 RNA Template strand direction Bmound transcript of DNA 9 Elongation Elongation Nontemplate strand of DNA Flewound N RNA R A nucleotides DNA polymerase 5 3 3i 5 5 3 RNA transcript 5 539 Direction of transcription downstream Template strand of DNA Newly made RNA Termination ending transcription termination sequence in DNA triggers RNA pol to release the DNA DNA and RNA polymerase dissociates l W 9 mRNA x dissociates xxxfrom DNA lNA polymerase g jfp DNA Four or more U ribonucleotides E Cytosine Guanine Adenine 1 D Uracil 7 5 quot mRNAhmmm causes RNA Promoter Transcription unit I T I I Start point DNA RNA polymerase 0 Initiation 3 I 5 RNA Template strand UNWOUNd transcript 0f DNA DNA 9 Elongation Rewound DNA 539 3 339 539 5 RNA transcri t p 6 Termination 3 l 539 I R Completed RNA transcript Copyright 2003 Pearson Education Inc publishing as Pearson Eenamin Cummings Review of Transcription Video review of transcription httphigheredmcgraw hilcomsitesOO72507470student viewOc hapter3animation mrna synthesis trans cription quiz 1 html Promoter Transcription unit 539 E l 3 3 l 4 39 5 Start point DNA RNA polymerase 0 Initiation 3 17 I 5 39 39 RNA Template strand unwound transcript of DNA DNA 9 Elongation Rewound DNA 3 5 5 RNA transcri t p 6 Termination 5 I 3 3 5 I I Completed RNA transcript Copyright 2008 Pearson Education Inc publishing as Pearson Bengamin Cummings 4122011 4122011 The template strand of a gene contain the sequence 3 TTCAGTCGT 5 Draw the non template sequence Draw the mRNA sequence Be sure to indicate the 5 and 3 ends of each Compare the two sequences mRNA Processing the finishing touches pre mRNA primary transcript contains large non coding regions introns l and coding regions exons w39 quot requires a cap and tail finished product is mRNA l m l P RNA 39 RNA PROCESSING 1mm mRNA quot17 1 h Processmg premRNA Involves two steps 1 RNA splicing gsome 2 Alterations to the ends k PO39VPeP deQj b Eukaryotic cell 5 Exon Intron Exon Intron Exon 3 a PremRNA quot a 7 7 7 7 1 30 31 104 105 146 lntrons cut out and Comm 1 exons spliced together segment mRNA 1 146 llsmnqas 5 3 mRNA Processing RNA splicing RNA transcript premRNA RNA Splicing removal of large composed of snRNPs and other proteins cuts introns and binds the exons together components Spliceosome l 5 Exon 1 Exon 2 Exon 1 Intron Exon 2 portions of the premRNA molecule g Protein 39 K m snRNA l a 39 V protelns Xi Spllceosome snRNPS the molecular complex that splices Spljrfeg me mRNA intron mRNA Processing alterations to the ends of pre mRNA Addition of the cap and tail The 5 cap a modified guanine nucleotide helps ribosomes attach to the mRNA so that translation can begin The polyA tail 50250 adenine A nucleotides protects the mRNA molecule from degradation by hydrolytic enzymes 4122011